Electronic Throttle Control (ETC) systems for gasoline-powered internal combustion engines, and Intake Throttle Valve (ITHV) systems for diesel-powered engines, commonly employ an Air Control Valve (ACV) that is actuated by a DC brush-type motor. The motor actuator responds to a closed-loop position control algorithm programmed into an Engine Control Module (ECM) to control air flow through the ACV, which in turn responds to engine operator input. For vehicular engines, the operator is the vehicle's driver.
The usage profile of the DC motor actuator is quite operator-dependent. Aggressive drivers will likely have aggressive throttle maneuvers, with rapid, large throttle position changes. Such changes are beneficial for cleaning the commutator and brushes of the motor actuator. Without an occasional large and rapid angular change requirement of the ACV, the DC motor commutator can acquire a build-up of material from the brushes. Further, there is opportunity for build-up of oxidation products on the brushes themselves. Either of such build-ups results in higher resistance of the brush motor, and therefore lower power output.
What is needed is a means for preventing significant build-up of contaminants, and especially commutation byproducts, on the commutators and brushes of a DC motor actuator for an intake air control valve on an internal combustion engine.
It is a principal object of the present invention to prevent significant build-up of contaminants, and especially commutation byproducts, on the commutator and brushes of a DC motor actuator for an intake air control valve on an internal combustion engine by periodically exercising an engine ACV, abruptly and rapidly, to the open and closed limits of its operating range. Preferably, such exercising should occur when such extremes cannot affect operation of the associated engine, such as before starting or after shutdown.